The login shell is the last field of a user's /etc/passwd line. Change another user's shell as root with chsh -s:
sudo chsh -s /usr/bin/zsh deploy
Change your own shell
Without a username, chsh changes your own shell (it prompts for your password):
chsh -s /usr/bin/zshusermod does the same thing as root and is the scriptable choice:
sudo usermod -s /usr/bin/zsh deployThe change takes effect at the next login, not in the current shell. To try a shell right now without making it permanent, just run it: zsh.
The shell has to be in /etc/shells
chsh only accepts shells listed in /etc/shells. If yours is missing, chsh refuses it:
cat /etc/shells # the allowed login shells
which zsh # where the shell actually isIf zsh is installed but not listed, add its path to /etc/shells (as root) and chsh will then accept it. usermod -s does not enforce /etc/shells, which is a footgun: it will happily set a path that does not exist and lock the user out of logging in.
Check the current shell
getent passwd deploy | cut -d: -f7 # the shell field for one user
echo "$SHELL" # your own current login shellA nologin shell disables interactive login
Setting the shell to nologin is how you keep a service account from being logged into, while it can still own files and run daemons:
sudo usermod -s /usr/sbin/nologin appsvcThis is also part of locking an account fully.
FAQ
Both set the login shell. chsh is interactive and validates the shell against /etc/shells, so it refuses an invalid path. usermod -s is scriptable and does not validate, so it can set a non-existent shell and lock the user out. Prefer chsh interactively, usermod in automation where you control the value.
The shell's path is not in /etc/shells. Confirm where it is with which zsh, then add that exact path to /etc/shells as root. chsh only accepts shells listed there.
A new login shell applies at the next login, not retroactively to an open session. Log out and back in, or just start the new shell directly (zsh) to use it immediately without changing the default.
See also
- How to Create a User on Linux: set the shell at creation with -s.
- Lock and unlock a user account: the nologin shell as a lockout.
- Run a command as another user: service accounts with no login shell.
- List users and groups: read the shell field across all accounts.
Sources
Authoritative references this article was fact-checked against.
